Loud speaker for use in wireless telephone apparatus



Sept. 29, 1925.

' w. H. JOHNS LOUD SPEAKER FOR USE IN WIRELESS TELEPHONE APPARATUS Filed March 2'7, 192

Patented Sept. 29, 1925. I

UNITED STATES HENRY JOHNS, OI BEIGA'IE, ENGLAND.

LOUD SPEAKER FOB IN WIRELESS TELEPfiONE APPARATUS.

Applioatioh ma larch :1, 1m. Berta! llo. 702,885.

To all whom it may concern:

Be it known that I, WILLIAM HnNnY JOHNS, a subject of the King of Great Bllt: ain, and resident of Reigate, 1n the county of Surrey, England, have invented certaln new and useful Improvements in and Relating to Loud Speakers for Use in Wireless Telephone Apparatus, of which the following is a specification.

This invention relates to loud speakers for use in connection with wireless a paratus.

One object of the invention 1s the provision of an improved magnet for vibrating the sound producing diaphragm.

Another object is the provlsion of an improved loud speaker which will be simple and durable of construction.

Other objects and advantages will appear hereinafter.

A loud speaker in accordance with the invention is illustrated in the accompanying drawings and the same will now be described it being understood that the particular construction illustrated is susceptible of various modifications without departing from the scope of the appended claim.

In thesedrawings Figure 1 is a sectional elevation of the loud speaker (minus the horn),

Figure 2 is a plan of the same but with the horn connection member and the diaphragm removed, and Figure 3 is a perspective View of the same.

Referring to the drawings, the sound reproducing'parts of the loud speaker are all contained in a non-magnetic cylindrical housing 1 supported by means of three legs 2 and adapted to support the horn (not shown) through the medium of a connection 0 member 3 which will be more particularly described hereinafter. I

The said sound reproducing parts consist of the usual magnetic diaphragm 4 secured over the open upper end of said housing 1 between the latter and the connection mem' her, and an electromagnet, indicated generally by the numeral 5, for effecting vibration of the said diaphragm. The cores of this electromagnet consist of two sets 7 of 0 magnetic laminations which'are respectively secured to two magnetic blocks 8, by means of'clamping brackets 8 said blocks 8 being mounted at opposite ends of a magnetic base plate 9. The cores 7 are, m the usual manner provided with respective windmgs' 10 and these windin are adapted to be energized by way of t e usual terminals 11.

The whole electromagnet above described is supported adjustably in such manner that the pole pieces 6 can be moved, within llmits, nearer to or further from the diaphragm 4; and. the support by which this is adapted to be efl'ected will now be described.

Depending vertically downwards from the centre of the base plate 9 and passing thrc'lough a bossed hole 12 in the closed lower en 0 the housing 1 isa brass or other non-' magnetic adjusting pillar 12. This pillar ing portion is screw rthreaded and has screwed-thereon an adjusting wheel 17 the centre boss of which is adapted to abut (with a. washer 18 in between) against the boss 18 of the hole 12".

The adjusting wheel 17 is prevented from being screwed right ofl the pillar 12 by means of a retaining screw 19.

From the .above it will be seen that the position to' which the wheel 17 is adjusted on the adjusting pillar 12 determined the highest position to which the electromagnet 5 can be moved. The electromagnet is permanently retained at such highest position by means of a non-magnetic spring support 20 beneath the plate 9 which permanently biases the electromagnet in the upward d rection. The electromagnet can thus be raised or lowered at will by rotation of the ,wheel 17. The extreme upward limit to the diaphragm 4 in between, to the housing 1 by means of screws 21, which 1pass loosely through slots 22 in the said diap ragm. The

connection member thus securely clam s the diaphragm in position without an anger of the latter being distorted.

The form of the connection member is clearly shown in the drawing. Outwardly it is trumpet shape, having a reduced spi ot 23 at its smaller and upperend on whic the horn is adapted to befitted. At 24 the said member is cut away as shown so as to give freedom to the diaphragm 4 in vibrat mg, and a hole 25 affords communication between said cutaway portion and the horn.

This hole is of taper formation lbeing lar er at its upper than at its lower end, and at 1ts said lower end it merges into the out awa portion 24 byway of a smooth curve as s own,

What I claim and desire to secure by Letters Patent is In a loud speaker for use in connection spectively on said blocks on the sides thereof remote from said base plate andwhereby the laminations of said pole pieces are bound together substantially as specified.

In witness whereof I aflix my signature.

wrLLiAM HENRY JOHNS. 

